Cloud computing has improved the flexibility and lowered the cost of information technology services for many entities, Host Machines provided by a Cloud Service Provider (CSP) enable entities to make use of shared infrastructure as tenants of the Host Machines to run instances of Virtual Machines (VM) or other cloud-based containers for services applications or processes, on an as-needed basis.
Shared infrastructure in the cloud allows millions of VMs to be hosted in data centers on Host Machines. In order to introduce new functionality, improve performance, fix security holes, patch bugs, or perform physical maintenance on host machines, however, it is frequently required that VM instances or the underlying Operating System of the host machine (HostOS) be taken offline and made unavailable, such as, for example, during a reboot of the host machine. This unavailability may result in a cached VM state being lost, tenants being prevented from accessing services when they are needed, service instances being unavailable to clients, etc., and constitutes a significant inconvenience.